Palladio v1.4.0

Foremost a bug-fix release to fix wrong texture paths of assets which were in different CityEngine projects than the main rule at RPK creation time (e.g. ESRI.lib).

Also streamlined the generated material attribute names - now using the generic "shader" names as documented for prtx::Material. So this may be a small breaking change, please update your material attribute mappings.

Attached to this release is another demo scene demonstrating how to wire up the generated material attributes to a built-in Houdini shader, e.g. Principled Shader.